Furnace-regulator system



Mar. 27, 1923. 1,449,889.

I c. A. BODDIE.

FURNACE REGULATOR SYSTEM.

FILED DEC.3 9l9- 2 SHEETSSHEET l- WITNESSES: INVENTOR Clarence Afioddl BY a ATTORNEY Mar. 27, 1923.

C. A. BODDIE. FURNACE REGULATOR SYSTEM.

FILED DEC-3,1915% 2 SHEETS SI'LEI WITNESSES: INVENTOR PatentedMar. 2 1923.

UNITED .STATES 1,449,889 PATENT OFFICE.

CLLRENCE'A. BQDDIE', F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC SYLVANIA.

MANUFACTURING COMPANY, A CORPORATION or PENN7 FURNACELREGULATOR SYSTEM.

v Application filedDecember 3, 1919. Serial No. 342,175.

To all whom it may concern Be it known that I, CLARENCE A. BODDIE, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Furnace-Regulator Systems, of which the following is a Specification.

My invention relates to regulator systems 10 and particularly to regulator systems for governing the operation of the, movable electrodes in electric furnaces.

One object of my invention is to provide a furnace-regulator system that shall govern the movements of each electrode in accordance with the current flowing through it to maintain a substantially constant arc and that shall be provided with a two-fold means for preventing so-called hunting action.

In operating electric furnaces, it is customary to govern the movement of each electrode in accordance with the current flowing through it and thus maintain a substantially constant electrode arc. However, such means for regulating the furnace is unsatisfactory unless some means is provided for insuring the system against hunting action.

In a furnace-regulator system constructed in accordance with my invention, each mov- 30 able elctrode is provided with a motor for raising and lowering it and a regulator is provided for eifectingthe operation of the motor in a clockwise and in a counter-clockwise direction in accordance with the value of the current flowing through the electrode. The regulator comprises a main control element having a main and an auxiliary electromagnet and two switches which are governed by the main control element for controlling the operation of the electrode motor.

The main magnet embodies a winding which is energized in accordance with the current flowing through the associated electrode and is provided with taps through which circuits are selectively completed by the switches for varying the active number of turns in the winding of the main magnet to change its setting and prevent the'so-called hunting action. The auxiliary electromagnet preferably comprises two windings which are constantly energized and a third winding which is disposed betweenthe first two windings and is energized in accordance with the counter-electromotive force of the electrode motor. Such arrangement of windingsin the v auxiliary 7 electromagnet provldes a polarized electromagnet so that the magnet operates in accordance with the direction of current flow through the motor armature.

A mechanical or energy-transmitting con motion is provided between the main and the auxiliary magnet whereby the main magnet is influenced in accordance with the operation of the auxiliary magnet to prevent hunting action. Each of the(two switches, which are operated by the mam control element for governing the direction of rotation of the electrode motor, comprise three windings. One of the windings'serves as a holding winding for'biasing the switch to a released position, and the other two windings serve to neutralize the holding winding and for operating the switch to an operative position. The switchesnot only'serve to govern the direction of rotation of the motor and to] vary the energization of the main magnet for preventing hunting action, but also to complete a dynamic-braking circuit through the electrode motor when simultaneously released.

In the accompanying drawing, Figure 1 is a diagrammatic view of a regulator system embodying my invention, and Fig. 2 is a .similar View of a modification of the system the electrode motor in accordance with the value of the current flowing through the associated electrode. Inasmuch as the motors and regulators associated with the various movable electrodes are similar in construction and operation, it is deemed sufficient' to describe the construction and operation of but one motor and one regulator, ngmely, the motor and regulator which are associated with the movable electrode 6.

An electric motor 10, comprisin an armature 1 1 and a field-magnet win ing 12, is provided for raising and lo'wering the electrode 6. .The field-magnet winding 12' is directly connected across a supply circuit comprising conductors 13 and 14, and the armature 11 is selectively connected across the supply conductors 13 and 14 by means pulley 19.

of switches 15 and 16. Switches 15 and 16 will be more fully described hereinafterbut for ,a complete disclosure thereof, reference is made to my copending application, Serial A. main control element 20, comprising a main magnet 21 and an auxiliary magnet 22, isprovided for governing the operation of i ,the switches 15 and 16 in accordance with the current flowing through the electrode 6.

The main magnet 21 comprises a winding 23 which is connected to the three-phase sup- 7 ply conductor 9 by means of a current transformer 24 in order to be energized in accordance with the current flowing through the electrode 6. .A plurality of taps 25, 26 and 27 sition of themain magn extend from thewinding 23 fora purpose to be hereinafter set forth. A core armature 28,.which ispivotally connected to a contact arm 29 and is operated by the winding 23, is provided witha piston 30 which operates within a cylinder 31 for changing the setting of the main magnet 21, under certain conditions, to prevent hunting action by the regulator. The contact arm 29 which is fulcrun ed at 32, carries a main contact member 33 that is adapted to engage contact mem bers 34 and 35 according to the operative poet 21. The auxiliary-electromagnet 22 comprises two windings 36 and 37, which are directly connected across the supply conductors 13 and 14, and a winding 38 which is disposed between the windings 36 and 37 and'which is connected across the armature ll of the motor 10 in order that it may be energized in accordance with the counter electromotive force of the electrode motor. The three windings 36, 37 and 38'operate upon a core armature 39 which is supported by a spring member 40*.and is provided with a piston 41.1The piston 41 is located for, operation within a cylinder 42. The two cylinders 31 'and 42 are connected by means of a pipe 43 ance with the operation of the auxiliary magnet 22. I

The movement-ofthe piston 41 within the cylinder 42, in accordance with the operation of the auxiliary magnet 22, varies the pressure that is exerted upon the piston 30, and, accordingly, changes the setting-of the main magnet 21. .Theoperation of the auxiliary magnet 22 is so controlledby the winding 38 as to change the setting of the ings 44, 45 and 46. The winding-46 is connected across the supply conductors 13 and 14 in series with a resistor 48 and serves to bias the armature 47'to a released position. The windings 44 and 45 are connected across the supply conductors 13 and 14 upon engagement' between the main contact members 33 and 35 and serve to neutralize the effect of the winding 46 and to move the armature 47 to an operative position for operating the motor 10 in a counter-clockwise direction. The winding 44 operates on a core armature 49 which is pivotally connected to an arm 50 .of the armature 47. The armature 47, which is fulcrumed at 51, comprises two arms 50 and 52,which are angularly disposed in relation to each other, and an interlock switch 53 which is connected to the arm 50. When the armature 47 is in a released position, as shown on the drawing, the arm52 engages the'co'ntact member 54 for completing a dynamic-braking circuit through the armature 11 of the motor 10 and, upon :movement of the armature 47 to an operative position, the arm 50 engages the contact .member 55 for'cvnnecting the armature 11 hunting action of the regulator when the electrode is being raised from the bath. of material.

The 1 switch 16 comprises three windings 56, 57 f and 58 which control the operation of an armature 59. The armature 59, which is fulcrumed at 60, comprises two arms 61 and 62 that are angularly disposed relative to each other. The contact arm 62, in the releasedposition of the switch, engages a contact member 63 to complete a dynamic-- braking circuit through the armature 11 of the motor 10. The arm 61, upon operation of the switch, engages a contact member 64 to connect the armature 11 across the supply conductors 13 and 14 to effect clockwise rotation of the motor. The arm '61 is provided with an interlock switch member 65 which serves, upon operation 0f the switch 16, to open a short-circuit which normally exists across that portion of the winding 23 which is included between the taps 26 and 25. Thus, the setting of the main magnet 21 is changed "to prevent hunt-- ing action when the electrode 6 is being lowered in the furnace. The winding 58 is permanently connected through the resistor 48 across the supply conductors 13 and 14 for biasing the armature 59 to a released position. The windin s 56 and 57 are con- 14 upon engagement between the main-contact members 33 and 34 and serve to neutralize the holding winding 58 and to move the armature 59 to an operative position. The winding 56 operateson a core armature'66 which is pivotally connected to the switch arm 61 of the armature 59.

nected across the supp y conductors 13 and If current below normal value flows through the electrode 6, the energization of the winding 23 is decreased for operating the switch arm 29 to efi'ect engagementbetween the contact members 33 and 34. Upon engagement. between the contact members 33 and 34, a circuit which is completed for operating the switch 16, extends from the of rotation of the motor 10. In the case supply conductor 13 through the switch arm 29, contact members'33 and34 and the windings 56 and 57 to the supply conductor 14. Thereupomthe holding power of the winding 58 is neutralized by the winding 57, and the winding 56 moves the switch arm. 61 into engagement with the contact member 64. A circuit is completed which extends from the supply conductor 14 through the contact member '54, switch arm 52, armature 1,1 of themotor 10,switch arm 61 and the contact member 64 to the supply conductor 13. Accordingly, the motor is operated in a clockwise direction to lower the electrode-6 in the furnace and to increase the current flow through the elec-. trode.

If no means were provided for preventing any huntingaction on the part of the regulator, the motor lO would continue to lower the electrode in the furnace until a normal amount of current was flowing through the electrode for increasin the energization of the main magnet to e ect separation ofthe main contact members 33 and 34. Consequently, the moving parts of the regulator and the armature of the motor 10 would overtravel to lower the electrode 6 beyond the point necessary to obtainnormal cur-' rent flow through the electrode circuit. In order to prevent such overtravel and the consequent hunting action, the interlock switch member 65 is operated simultaneously with the motor 10 for opening the shortcircuit which obtains across that portion of the winding 23 which is included between the taps and 26. Thus, the energization of the main magnet 21 is increased to change the setting of such magnet and to effect operation of the contact arm 29 to sepalator is not only prevented by varying rate the contact members 33 and 34 just prior to the obtainin of normal current flowthrough the circuit of the electrode 6. Hunting action on the part of the reguenergization of the main magnet 21 but is also insured against by the operation of the auxiliary magnet 22. Thus, in the case under consideration, the winding 38 of the auxiliary magnet is energized by the counter-electromotive force of the motor 10 for moving the core armature 39 and the piston 41 downwardly and, consequently, the pressure upon the bottom of the piston 30 of the main magnet 21 is increased tochange the setting of such magnet and, thereby, its tendency to eifect a separation of the con tact members 33 and 34 just prior to the obtaining of normal current flow through the electrode 6. It will be noted that, inasmuch as the auxiliary magnet 22 operates as a polarized electromagnet, it is possible to operate the piston 41 in either direction, as desired, in accordance with the direction under consideration, it is assumed that the ,plunger 41 is lowered when the motor is operated in a clockwise direction and is raised when the motor is operated in a counter-clockwise direction. If current above normal value flows through the electrode 6, the energization of the main magnet 21 is increased to efi'ect engagement of the .contact members 33 and Upon engagement of the contact members. 33 and 35, a circuit, which is com- .pleted for operating the magnet 15, extends which extends from the supply conductor 14, through the contact member 63, switch arm 62, armature 11, switch arm 50 and the contact member 55 to the supply conductor 13. Accordingly, the motor 10 is operated in a counter-clockwise direction for raising the electrode 6 to reduce the current flow through the electrode circuit.

In order to prevent hunting action when the motor 10 is being operated in acounterclockwise direction to raise the electrode 6, the interlock switch member 53 is operated simultaneously with the motor 10 to shortcircuit that portion of the winding 23 which is included between the taps 26 and 27. Thus,.the energization of the main magnet 21 is decreased to change the setting of such magnet in order to effect separation of the contact members 33 and 35 just prior to the obtaining of normal current flow through the electrode 6..

The operation of the motor also serves to eliect operation of the auxiliary magnet 22 for preventing any hunting action by the' regulator. Thus, the operation of the motor 10 in the counter-clockwise direction energizes the winding 38 in a manner to raise the core armature 39 and the piston 41. The raising of the piston 41 reduces the pressure which is exerted upon the bottom of the piston and, consequently, changes the setting of the magnet 21 to permit-separation of the contact members 33 and 35 just prior to the obtaining of normal current flow through the electrode 6.

The system illustratedin Fig. 2' of the v drawing is similar in operation and some- ,what similar in construction to the system.

illustrated in Fig. 1 of the drawing and, accordingly, a complete description of the operation of the system shown in Fig. 2

Moreover, similar parts in (Fig. 2 of the drawing have'been is deemed unnecessary.

referred to by corresponding reference nu- -merals. The system shown in Fig. 2 of the drawing difi'ers from the system shown in Fig. 1 chiefly in the-mechanical connectlon between the main and the auxiliary electromagnets and in the operation of the switches which are operated by the main control element.

Referring to Fig. 2 of the drawing, the main 7 and the auxiliary electromagnets 21 and 22, which are respectively provided with dash pots 70 and 71 for adjusting their operation, are connected to opposite ends of a contact arm 72. The contact arm 72 is fultion of the main control element.

- Two switches 79 and 80 are governed by the main control element for operatingthe inotor 10 in a counter-clockwise and in a clockwise direction to govern the amount of current' flowing through the electrode 6'. The switch 79 comprises a winding 79 which isconnected across the supply conductors 13 and 14 upon engagement-between .the contact members 74 and 7 6. The winding 79 controls a core armature 81 which is directly connected to two switch members 82 and 83 and two interlock switch members;

direction.

84 and 85 The two switch members 82 and 83 serve to connect the armature 11 across thesupply conductors 13 and 14 for operating the motor 10 in a counter-clockwise The interlock switch 84, upon operation of the switch 79,- completes a circuit for short-circuiting that portion-of the winding 23 which is included between the taps 25 and 26 for reducing the energize.-

tion of the main magnet 21 to prevent any hunting action.

The switch 80 comprises a winding 86, which is connected across the supply conductors 13 and 14 upon engagement between the main contact members 74 and 7 5, and a 'core armature 87, which is controlled by the winding 86. The core armature 87 isdirectlyconnected to two switch members 88 and 89 and two interlock switch members 90 and '91. The two switch members 88 and I 89, upon operation of the switch 80, connect the armature 11 across the supply conductors 13 and 14 for operating the motor 10 in a clockwise direction. lhe interlock switch member 90, upon operation of the switch 80, serves to. open a short-circuit which normally obtains acros that portion of the current winding 23 which is included between the taps 26 and 27 and, accordingly, to increase the energization of the main magnet 21 and prevent any hunting action when the electrode 6 is being lowered in the furnace;

\Vhen the two switch members 79 and 80 are simultaneously de-energized, the interlock switch members and connect the energizing Winding of thebrake relay 92' across the supplyconductors- 13 and 14. Uponoperation of the brake relay 92, a dynamic-braking circuit for the armature 11 is completed through a resistor 93. Thus, when the motor 10 is operated in a counterclockwise or aclockwise direction for respectivelyraising or lowering the electrode- 6, a dynamic-braking. circuit is completed upon the release of the switch 79 or the switch 80, as the case may be, for effecting a quick stopping-of the motor.

If current above normal value through the "electrode 6, the energiaa' tion of the main magnet 21 is creased to operate the contact arm 72 and eifect engagement between the contact members 74 and 76. Upon engagement between the contact members 74 and 76, 'acircuit is completedfromzthe supply. conductor '13 through the contact arm 72, contact members 74 and 76 and the winding 81 to the supply "conductor 14. The switch 79;is operated and a circuit is completed which extends from the supply conductor 13 through the switch member 82, armature 11, and the switch member 83 to the supply conductor 13. Thereupon, the moto r 10 is operatedin a counter-clockwise direction,

for raising the electrode 6 to decrease the current flow through it.

The interlock switch member 84 is operated simultaneously with the. motor 10 for short-circuiting a portion of the winding 23 of the main magnet 21 inorder to change the setting of the main control element and 5 and operation to the auxiliary for operating the thus prevent the so-ca7lled hunting action. The settingof the main control element 20 is so changed that separation of the contact members 74 and 76 is effected just prior to the obtaining of normal current flow through the electrode 6, and, consequently, overtravel of the various moving parts of the regulator and of the motor is prevented. I

Hunting action is not only insured against by the variation in the energization of the main magnet 21 but also by the operation of the auxilia magnet 22. The auxiliary magnet is simi ar in construction magnet shown in Fig. 1 of the drawing. However, in the system shown inFig. 2, the auxiliary magnet is directly connected to the contact arm 72 and it opposes the action of the main magnet 21 through the contact arm. In the case under consideration, the auxiliary magnet 22 is operated to separate the contact members 74 and 76 when the motor is being operated in a counter-clockwise direction. It is to be understood that the elfect of the variation in the energization of the main magnet 21 and of the auxiliary magnet 22 is so adjusted as to separate the contact members 74 and 76 just prior to the, obtaining of normal current flow through the electrode 6.

If the current flow through the electrode 6 is below normal value, of the main magnet 21 is decreased to effect pleted from the s pply conductors 13 and 14 switch 80 to effect clockwise rotation of the motor 10. Upon operation of the motor 10 in a clockwisedirection, the'electrode 6 is lowered in the furnace to increase the current flow through the electrode circuit. The interlock switch member 90 is operated simultaneously with the motor 10 for opening the short-circuit which normally obtains across that portion of the winding .23 which is included between the taps 26 and 27 for increasing the energiza-' tion of the main magnet 21 to change its -setting. The setting of the main magnet 21 is changed in order that the main contact members 74 and 75 shall be separated just prior to the obtaining of normal cur- I rent flow through the electrode 6c and, ac eordingly, prevent overtravel with the consequent hunting action. At the same time, 4 the, auxiliary magnet 22 1s ener 'zed by the m counter-electromotive force of t e motor 10 to separate the contactmembers 74 and 75 a and to assist in preventing hunting action.

. From the above description, it will be noted that each'ele'ctrode motor is operated 55 in accordance with the current flowing through the associated electrode for main- .ment and location of the energization,

engagement between the contact members 7 4 A and 75. Upon engagement between the con- 'tact members 74 and 75, a circuit is comthe terms energy but the auxiliary magnet is In my copending ,application, Serial N o. 319,906, filed August 26, 1919, I have illustrated, described and claimed a furnaceregulator system having another means for preventing hunting action.

Modifications in the system and arrangeparts may be made within the spirit and scopeof my-invent on, and such modifications are intended to be covered by the appended claims.

I claimas my invention:

1. In a furnace-regulator system, the combination with a movable electrode, a motor for raising and lowering the electrode, and

a main magnet for governing the operationof said motor in accordance with the current flowing through mechanically and electrically governing the operation of the hunting action.

2. In a-furnace-regulator system, the combination comprising a movable electrode, a motor for raising and lowering said electrode, a mam magnet operated 1n accordance :with electrode circuit conditions for controlling said motor, and means for electrically and mechanically influencing the operation of the main hunting action.

3. In a furnace-regulator system, the combination comprising a movable electlrode, means comprising an electromagnet for governing the operation of said electrode in accordance with-electrode circuit conditions, and means for electrically and mechanically influencing the operation of said magnet to prevent hunting action.

4. In a -furnace-regulator system, the combination comprising a movable electrode, means comprisingan electromagnet for governing the operation of said electrode in accordance with electrode-circuit conditions and two separate means for influencing the operation of said magnet to prevent hunting action. Y 4

5. In a furnace-regulator system, the combinationicomprising a movable electrode, a motor for raising and lowering" the electrode, means comprising a main magnet for governing the operation. of said motor n accordance with electrode-circuit conditions to maintain a const nt ele trede ar e ns main magnet to prevent the electrode," of means for I magnet to prevent" for varying the energization of said magnet to prevent hunting action, and mechanical means varied in accordance with the operation of said motor for influencing the magu 5 net to prevent hunting action.

6. In a furnace-regulaton system, the combination with a movable electrode, a motor 'for raising and lowering the electrode, and means comprising a main magnet energized I 19 in accordance with the current flowing through the electrode for maintaining a, constant electrode arc, of means comprising two switches for varying the active number of turns insaid magnet to prevent hunting action, and an auxiliary magnet controlled by said switches and acting on the main magnet to prevent hunting action.

7 In a furnace-regulator system, the conbination with amovable electrode, means 20 for raising and lowering said electrode, and

.2 iliary ma net and for directly influencing the operatlon of the main magnet to prevent hunting action,

8. In a furnace-regulator system, the co-m bination with a movable electrode, a motor for raising and lowering the electrode, and

a main magnet for controlling the operation of the motor in accordance with the current flowing through the electrode, of an auxiliary magnet, and means for controlling the auxiliary magnet to mechanically influence the main magnet and prevent hunting action and for varying the active number of turns in the winding of the main .magnet to prevent hunting action.

9. In a furnaceregulator system, the combination'with a movable electrode, a motor I for raising andlowering said electrode, and

a main magnet for controlling the operation of said motor in accordance with the current flowing throughthe electrode, of an auxillary magnet having two constantly energized windings. and a third winding, disposed between said two windings, means for, energizing said third winding in accordance with the operation of said motor, and a a mechanical connection between said magnets for influencing the main magnet in accordance with the operation of the auxiliary magnet to prevent hunting action.

10. In a furnace-regulator system, in combination, a movable electrode, means comprislnga main magnet for controlling the operation of the movable electrode in ac cordance with the current flowing through it,'an auxiliary'magnet having a mechanical connection to the main magnet, and means for operating the auxiliary magnet in accordance with the cou-nter-electro motive force of the motor to influence the main magnet and prevent hunting action.

incense 11. In a furnace-regulator system, the I combination with a'movable electrode, a

motor for operating the electrode, and means comprising a main magnet for controlling the operation of the motor in accordance with the current flowing through the electrode, of an auxiliary magnet, means for polarizing the auxiliary magnet and for operating it in accordance with the operation of the motor, and means for influencing the main magnet in accordance with'the operation of the auxiliary magnet to prevent hunting action.

12.' In a furnace-regulator stem, the combination with a movable e ectrodje, a motor for operating the electrode and means comprising a main magnet for controlling the operation of the motor in accordance with the current flowing through the electrode, of an auxiliary magnet, means for operatingsaid auxiliary-magnet in accordance with the counter-elect-romotive force of the motor, and a mechanical connection between said magnets for operating the main magnet in accordance with the operation of the auxiliary 'magnet to prevent hunting action.

13. In a furnace-regulator system, the combination with a movable electrode, and a motor for raising and lowering said electrode, of means comprising'two switches for controlling the operation of said motor in accordance with the current flowing through the electrode to maintain a constant electrode are, each of said switches comprising a constantly energized winding for biasing the switch to a released position and two windings for operating the switch and for neutralizing said first winding.

14. In a furnace-regulator system, the combination with a movable electrode, and a motor for operating said electrode, of

a main control element for controlling the operation of said motor in accordance with the current flowing through the electrode,

said element comprising a main magnet energized in accordance with'the current flowing through the electrode and an auxiliary polarized electromagnet having a polarizing and an operating winding, means for varying the energization' ofsaid main magnet to prevent hunting, and means for varying the energizatlon of the operating winding of said auxiliary magnet in accordance with the energization of the electrode motor 'to prevent hunting action,

15. tion with a supply circuit and an energy. translation device associated therewith, of regulator mechanism therefor comprising a control electromagnet and a plurality of independent devices associated therewith for preventing hunting action in said system.

In a regulator system, the combina- 16. In a regulator system, the combination I with a supply circuit and an energy-translating device associated therewith, of regulator mechanism therefor comprising a control electromagnet and two means for preventing hunting action in said system.-

17. In a regulator system, the combination with a supply circuit, a resistance-varyingmem'ber associated therewith, and means for operating said member, of regulator mechanism therefor comprising a plurality of electromagnets and means associated with each of said electromagnets for'preventing hunt-in action in said system.

18. fn a furnace-regulator system, the combination with an electrode, and a motor for raising and lowering said electrode, of

regulator mechanism therefor comprising a plurality of electromagnets, and means associated with each of said electromagnets for preventing hunting action in said system.v

19. In a furnace-regulator system, the combination with a movable electrode and a motor for moving said electrode, of regulator mechanism therefor controlled in accordance with an electrical characteristic of the electrode circuit and two means for preventing hunting action in said system.

,20. In a furnace regulator, the combination with a movable electrode, a motor for lator mechanism adapted to control the operation of said switches in accordance with an electrical characteristic of the electrode circuit.

21. In a furnace regulator, the combination with a movable electrode, a motor for moving said electrode, and a plurality of switches for controlling the operation of sald motor, each of said switcheshavmg a contact arm,,means for operating said arm to one position and electrical meansfor actuating said arm to a second position and holding the same in said second position, of regulator mechanism adapted to control the operation of said switches in accordance with an electrical characteristic of the electrode circuit.

22. In a furnace regulator, the combination with a movable electrode, a motor for moving said electrode, switching means for controlling the operation of said motor, said switching means'comprising means for operating'said switch to actuate said motor and also additional means for returning the switch to its non-actuating position, of regulator mechanism adapted to control the operation of said switching means in 'accordance with an electrical-characteristic of the electrode circuit.

23. In a furnace regulator, the combination with a movable electrode, a motor for moving said electrode, and switching means movable in two directions for controlling the operation of said motor and a dynamic braking circuit therefor, said switching means comprising means for actuating the switch in both directions and retaining the, same 111 one posit on, of regulator mechanism adapted to control the operation of said switching means in accordance with an electrical characteristic of the electrode cir- 'cuit-..

24. In a furnace regulator, the combination with a movable electrode, a motor for moving said electrode, and switching means for controlling the operation of said motor and a dynamic-braking circuit therefor, said switching means being normally positively actuated to complete said dynamic-braking circuit and having means for actuating the Same to initiate the operation of said motor, of regulator mechanism adapted to control the operation of said switching means in accordance with an electrical characteristic of the electrode circuit.

In testimony whereof, I have hereunto subscribed my name this 29th day of. November, 1919.

CLARENCE A. BODDIE. 

